A sandwich-like nano-micro LDH-MXene-LDH for high-performance supercapacitors.

• The band structure and density of states indicates a high electron transfer. • The structure integrates macroporous structure and stable interconnection. • The supercapacitor gains a good rate retention and long-term cycling stability. The sandwich‐like nano-micro LDH-MXene-LDH is synthesized by the coprecipitation method. The design of MXene@Ni-Mn LDH is estimated by the band structure and partial density of states using density functional theory. MXene as a carrier can promote the electron conductivity of Ni-Mn LDH to improve the rate retention. LDH can uniformly cover MXene surface to provide more available active sites for the capacitance enhancement. The electronic coupling between Ni-Mn LDH and MXene can improve the electron transfer and ensure the structure stability for the long-term cycling. As a three-electrode cell, MXene@Ni-Mn LDH exhibits the enhanced capacitance and rate retention by the synergistic effect. The asymmetric supercapacitor gains the energy density of 44.7 Wh kg−1 at the power density of 800 W kg−1 and maintained the 90.3% of the initial capacitance after 5000 cycles. [ABSTRACT FROM AUTHOR]